Multidisciplinary Optimisation of High Pressure Turbine Blade Tip With Turbine Inlet Capacity and Stage Reaction Constraints

The unsteady aero-dynamics of a single-stage high-pressure turbine blade operating at design corrected conditions has been the subject of a thorough study involving detailed measurements and computations. The experimental configuration consisted of a single-stage high-pressure turbine and the adjacent, downstream, low-pressure turbine nozzle row. All three blade-rows were instrumented at three spanwise locations with flush-mounted, high frequency response pressure transducers. The rotor was also instrumented with the same transducers on the blade tip and platform and the stationary shroud was instrumented with pressure transducers at specific locations above the rotating blade. Predictions of the time-dependent flow field around the rotor were obtained using MSU-TURBO, a 3D, non-linear, computational fluid dynamics (CFD) code. Using an isolated blade-row unsteady analysis method, the unsteady surface pressure for the high-pressure turbine rotor due to the upstream high-pressure turbine nozzle was calculated. The predicted unsteady pressure on the rotor surface was compared to the measurements at selected spanwise locations on the blade, in the recessed cavity, and on the shroud. The rig and computational models included a flat and recessed blade tip geometry and were used for the comparisons presented in the paper. Comparisons of the measured and predicted static pressure loading on the blade surface show excellent correlation from both a time-average and time-accurate standpoint. This paper concentrates on the tip and shroud comparisons between the experiments and the predictions and these results also show good correlation with the time-resolved data. These data comparisons provide confidence in the CFD modeling and its ability to capture unsteady flow physics on the blade surface, in the flat and recessed tip regions of the blade, and on the stationary shroud.

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Numerical investigation of high-pressure turbine blade tip flows: analysis of aerodynamics

Proceedings of the Institution of Mechanical Engineers Part A Journal of Power and Energy ◽

10.1177/0957650911412871 ◽

2011 ◽

Vol 225 (7) ◽

pp. 940-953 ◽

Cited By ~ 3

Author(s):

P Vass ◽

T Arts

Keyword(s):

High Pressure ◽

Turbine Blade ◽

Three Dimensional ◽

Suction Side ◽

Point Of View ◽

Internal Cooling ◽

High Pressure Turbine ◽

Blade Tip ◽

Design Solutions ◽

Exit Mach Number

The current contribution reports on the validation and analysis of three-dimensional computational results of the flow around four distinct high-pressure turbine blade tip geometries (TG1, 2, 3, and 4 hereinafter), taking into account the effect of the entire internal cooling setup inside the blade, at design exit Mach number: M = 0.8, and high exit Reynolds number: Re C = 900 000. Three of the four geometries represent different tip design solutions – TG1: full squealer rim; TG2: single squealer on the suction side; TG3: partial suction and pressure side squealer, and one (TG4) models TG1 in worn condition. This article provides a comparison between the different geometries from the aerodynamic point of view, analyses the losses, and evaluates the distinct design solutions. An assessment of the effect of the uneven rubbing of the blade tip was performed as well. TG1 was found to be the top performer followed by TG3 and TG2. According to the investigations, the effect of rubbing increased the kinetic loss coefficient by 10–15 per cent.

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Averaged and Time-Dependent Aerodynamics of a High Pressure Turbine Blade Tip Cavity and Stationary Shroud: Comparison of Computational and Experimental Results

Journal of Turbomachinery ◽

10.1115/1.1934410 ◽

2004 ◽

Vol 127 (4) ◽

pp. 736-746 ◽

Cited By ~ 20

Author(s):

Brian R. Green ◽

John W. Barter ◽

Charles W. Haldeman ◽

Michael G. Dunn

Keyword(s):

High Pressure ◽

Turbine Blade ◽

Computational Models ◽

Single Stage ◽

Time Dependent ◽

Cfd Modeling ◽

Blade Surface ◽

High Pressure Turbine ◽

Pressure Transducers ◽

Blade Tip

The unsteady aero-dynamics of a single-stage high-pressure turbine blade operating at design corrected conditions has been the subject of a thorough study involving detailed measurements and computations. The experimental configuration consisted of a single-stage high-pressure turbine and the adjacent, downstream, low-pressure turbine nozzle row. All three blade-rows were instrumented at three spanwise locations with flush-mounted, high-frequency response pressure transducers. The rotor was also instrumented with the same transducers on the blade tip and platform and the stationary shroud was instrumented with pressure transducers at specific locations above the rotating blade. Predictions of the time-dependent flow field around the rotor were obtained using MSU-TURBO, a three-dimensional (3D), nonlinear, computational fluid dynamics (CFD) code. Using an isolated blade-row unsteady analysis method, the unsteady surface pressure for the high-pressure turbine rotor due to the upstream high-pressure turbine nozzle was calculated. The predicted unsteady pressure on the rotor surface was compared to the measurements at selected spanwise locations on the blade, in the recessed cavity, and on the shroud. The rig and computational models included a flat and recessed blade tip geometry and were used for the comparisons presented in the paper. Comparisons of the measured and predicted static pressure loading on the blade surface show excellent correlation from both a time-average and time-accurate standpoint. This paper concentrates on the tip and shroud comparisons between the experiments and the predictions and these results also show good correlation with the time-resolved data. These data comparisons provide confidence in the CFD modeling and its ability to capture unsteady flow physics on the blade surface, in the flat and recessed tip regions of the blade, and on the stationary shroud.

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Multi-Disciplinary Analyses for the Design of a High Pressure Turbine Blade Tip

Volume 5A: Heat Transfer ◽

10.1115/gt2016-57794 ◽

2016 ◽

Author(s):

Stefano Caloni ◽

Shahrokh Shahpar

Keyword(s):

High Pressure ◽

Turbine Blade ◽

Turbine Blades ◽

Suction Side ◽

High Pressure Turbine ◽

Cooling Flow ◽

Barrier Coating ◽

Flow Features ◽

Internally Cooled ◽

Blade Tip

The design of a high pressure turbine blade is a challenging task requiring multiple disciplines to be solved simultaneously. Most recently, conjugate analyses are being developed to tackle such a problem; they are able to resolve both the fluid dynamics in a turbine passage and the thermal distribution in the solid part of the component. In this paper, the in-house Hydra CFD solver is used to analyse a high pressure shroudless turbine blade for a modern jet engine. The turbine is internally cooled and a Thermal Barrier Coating (TBC) is applied on the aerofoil surface. The coupling technique used at the interface in the presence of the TBC is described. The flow features at the tip of the turbine blade are the main focus of this study. Four different tip configurations are analysed. A flat tip and a squealer tip are chosen as reference designs; however the effects of opening the Trailing Edge (TE) on the Suction Side (SS) and the Pressure Side (PS) are also investigated. Both a cooled and an uncooled configuration of the turbine blade are analysed and the effect of the cooling flow on the over tip leakage is studied. Finally, conjugate analyses for the cooled turbine blades are used to predict the temperature reached by the different tip designs. The design with an opened TE on the SS shows a significant aerodynamic improvement over the others without increasing the temperature the tip has to withstand in operation.

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Computational Modeling and Thermal Paint Verification of Film-Cooling Designs for an Unshrouded High-Pressure Turbine Blade

Volume 3: Heat Transfer; Electric Power; Industrial and Cogeneration ◽

10.1115/99-gt-330 ◽

1999 ◽

Cited By ~ 2

Author(s):

Steven G. Gegg ◽

Nathan J. Heidegger ◽

Ronald A. Mikkelson

Keyword(s):

Heat Transfer ◽

High Pressure ◽

Turbine Blade ◽

Film Cooling ◽

Data Exchange ◽

Turbine Blades ◽

Inlet Temperature ◽

High Pressure Turbine ◽

Extreme High Temperature ◽

Blade Tip

High pressure turbine blades are exposed to an extreme high temperature environment due to increasing turbine inlet temperature. High heat fluxes are likely on the blade pressure surface. Other regions, such as the trailing edge and blade tip may be difficult to cool uniformly. Unshrouded blades present an additional challenge due to the pressure driven transport of hot gas across the blade tip. The blade tip region is therefore prone to severe thermal stress, fatigue and oxidation. In order to develop effective cooling methods, designers require detailed flow and heat transfer information. This paper reports on computational aerodynamics and heat transfer studies for an unshrouded high pressure turbine blade. The emphasis is placed on the application of appropriate 3-D models for the prediction of airfoil surface temperatures. Details of the film cooling model, boundary conditions and data exchange with heat transfer models are described. The analysis approach has been refined for design use to provide timely and accurate results. Film cooling designs are to be tailored for the best coverage of the blade tip region. Designs include near-tip pressure side films and blade tip cooling holes. Hole placement and angle are investigated to achieve the best coolant coverage on the blade tip. Analytical results are compared to a thermal paint test on engine hardware. In addition to film cooling strategies, other aerodynamic/heat transfer design approaches are discussed to address the cooling requirements for an unshrouded blade.

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Optimization of a high pressure turbine blade tip cavity with conjugate heat transfer analysis

Journal of Mechanical Science and Technology ◽

10.1007/s12206-016-1121-6 ◽

2016 ◽

Vol 30 (12) ◽

pp. 5529-5538 ◽

Cited By ~ 6

Author(s):

Jinuk Kim ◽

Young Seok Kang ◽

Dongwha Kim ◽

Jihyeong Lee ◽

Bong Jun Cha ◽

...

Keyword(s):

Heat Transfer ◽

High Pressure ◽

Turbine Blade ◽

Conjugate Heat Transfer ◽

Heat Transfer Analysis ◽

High Pressure Turbine ◽

Blade Tip

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Erratum to “Optimization of a high pressure turbine blade tip cavity with conjugate heat transfer analysis”

Journal of Mechanical Science and Technology ◽

10.1007/s12206-016-1251-x ◽

2017 ◽

Vol 31 (1) ◽

pp. 479-479

Author(s):

Jinuk Kim ◽

Young Seok Kang ◽

Dongwha Kim ◽

Jihyeong Lee ◽

Bong Jun Cha ◽

...

Keyword(s):

Heat Transfer ◽

High Pressure ◽

Turbine Blade ◽

Conjugate Heat Transfer ◽

Heat Transfer Analysis ◽

High Pressure Turbine ◽

Blade Tip

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Overtip Shock Wave Structure and Its Impact on Turbine Blade Tip Heat Transfer

Journal of Turbomachinery ◽

10.1115/1.4002949 ◽

2011 ◽

Vol 133 (4) ◽

Cited By ~ 55

Author(s):

Q. Zhang ◽

D. O. O’Dowd ◽

L. He ◽

A. P. S. Wheeler ◽

P. M. Ligrani ◽

...

Keyword(s):

Heat Transfer ◽

Shock Wave ◽

High Pressure ◽

Supersonic Flow ◽

Turbine Blade ◽

High Speed ◽

Wave Structure ◽

Shock Wave Structure ◽

High Pressure Turbine ◽

Blade Tip

In this paper, the transonic flow pattern and its influence on heat transfer on a high-pressure turbine blade tip are investigated using experimental and computational methods. Spatially resolved heat transfer data are obtained at conditions representative of a single-stage high-pressure turbine blade (Mexit=1.0, Reexit=1.27×106, gap=1.5% chord) using the transient infrared thermography technique within the Oxford high speed linear cascade research facility. Computational fluid dynamics (CFD) predictions are conducted using the Rolls-Royce HYDRA/PADRAM suite. The CFD solver is able to capture most of the spatial heat flux variations and gives prediction results, which compare well with the experimental data. The results show that the majority of the blade tip experiences a supersonic flow with peak Mach number reaching 1.8. Unlike other low-speed data in the open literature, the turbine blade tip heat transfer is greatly influenced by the shock wave structure inside the tip gap. Oblique shock waves are initiated near the pressure-side edge of the tip, prior to being reflected multiple times between the casing and the tip. Supersonic flow within the tip gap is generally terminated by a normal shock near the exit of the gap. Both measured and calculated heat transfer spatial distributions illustrate very clear stripes as the signature of the multiple shock structure. Overall, the supersonic part of tip experiences noticeably lower heat transfer than that near the leading-edge where the flow inside the tip gap remains subsonic.

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Heat-Flux Measurements and Predictions for the Blade Tip Region of a High-Pressure Turbine

Volume 3: Heat Transfer, Parts A and B ◽

10.1115/gt2006-90048 ◽

2006 ◽

Cited By ~ 12

Author(s):

S. M. Molter ◽

M. G. Dunn ◽

C. W. Haldeman ◽

R. F. Bergholz ◽

P. Vitt

Keyword(s):

Heat Flux ◽

High Pressure ◽

Steady State ◽

Flow Field ◽

Turbine Blade ◽

Heat Load ◽

Complex Flow ◽

High Pressure Turbine ◽

Blade Tip ◽

Blade Tips

High-pressure turbine blade tips operate in a highly complex flow environment that makes designing new blades for increased life difficult. Computational fluid dynamics simulations of the tip flow field may be able to guide new designs to improve the blade life, but the analysis techniques need to be verified against detailed measurements before they can be applied. The current paper presents measurements of heat flux and pressure in the blade tip region of a modern one-and-one-half stage high-pressure turbine operating at design corrected conditions in a rotating rig. Both flat tip and recessed, or squealer, tip blades were used in the experiments. The measurements indicate that the recessed tip, used in the majority of modern turbines to minimize blade damage from rubs, increases the blade heat load overall, and creates several hot spots on the floor of the recess for an uncooled airfoil. The tip data also showed there were significant unsteady variations in the heat load at the vane passing frequency. Steady state CFD calculations were completed for both flat and squealer tip configurations to examine if the analysis could capture the details that were measured. The CFD, while not capable of estimating the unsteady heat load component and generally over predicting the overall heat flux by 10–25%, did capture the measured heat flux trends in the recessed tip. These results show that steady-state CFD analysis can be useful in predicting the complex flow field and heat load distribution in turbine blade tips to help guide future blade designs.

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